A transparent ceramic high-temperature oxidation-resistant glass coating of nitrogen oxides and a method for preparing the same

Abstract

The application discloses a nitroxide transparent ceramic high-temperature oxidation-resistant glass coating, which is prepared by first preparing slurry by taking mullite powder and glass powder as main raw materials, coating the slurry on the surface of a nitroxide transparent ceramic substrate, and then performing pre-solidification and sintering. In the application, mullite powder is introduced into the slurry of a high-silicon-aluminum-calcium-zinc-based glass coating, and during high-temperature sintering, the Al and Si-rich glass phase in the glass system is precipitated in the form of fine mullite crystal phase around the mullite, and a mullite whisker structure is formed, which is beneficial to the effective fusion of the mullite and the glass phase. The glass coating can provide good oxidation protection for the substrate material at 1200 DEG C, ensure good high-temperature optical performance, and significantly improve the high-temperature resistance, heat insulation performance, surface wear resistance and acid and alkali resistance of the ceramic coating material, and can provide a new idea for the high-temperature oxidation-resistant technology of nitroxide transparent ceramics.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature oxidation-resistant technology of transparent nitride ceramics, specifically relating to a high-temperature oxidation-resistant glass coating of transparent nitride ceramics and its preparation method. Background Technology

[0002] Transparent nitride ceramics (such as spinel-type compounds like MgAlON, AlON, and LiAlON) are characterized by corrosion resistance, wear resistance, impact resistance, high hardness, high strength, and good electrical insulation properties. They also have excellent optical properties, exhibiting good optical transmittance in the ultraviolet, visible, and infrared light bands. As a result, they are widely used in missile fairings, high-temperature optical windows, transparent armor, mobile phone screens, and advanced camera lenses.

[0003] However, nitrogen oxides are inevitably oxidized in high-temperature oxidizing atmospheres (J Ceram Soc Jpn115.1343(2007):409-413.), which alters the surface phases, composition, and structure of transparent ceramic materials. The reduced optical transmittance resulting from surface oxidation affects the high-temperature performance of the material in industrial containers. In the field of ceramic materials, the common measure to prevent high-temperature oxidation of nitrogen oxide materials is to add a certain amount of antioxidants to the material, but the transparency of the ceramic matrix is ​​often overlooked. For example, SiC-AlON ceramic composites (Process and Appl Ceram, 2022, 16(2): 97-105.), BN-MgAlON ceramic composites (J Iron and Steel Res Int, 2015, 22(5): 423-430.), Si3N4-MgAlON ceramic composites (Key Eng Mater, 2005, 280-283(II): 1335-1338.), etc., the addition of these antioxidants can lead to problems such as the generation of second-phase impurities in transparent ceramics, which in turn affects the transparent ceramics.

[0004] Nitrogen oxide transparent ceramics require high precision in terms of phase composition after sintering. Introducing antioxidants and other additives into the matrix can negatively impact the optical and mechanical properties of the material. Further exploration and optimization of high-temperature oxidation resistance techniques for oxide transparent ceramics are of significant research and application value. Summary of the Invention

[0005] The main objective of this invention is to address the problems and shortcomings of existing technologies by providing a high-temperature anti-oxidation glass coating for transparent oxynitride ceramics and its preparation method. By introducing mullite powder into a high-silicon-aluminum-calcium-zinc based glass coating slurry, during high-temperature sintering, the Al- and Si-rich glass phase in the glass system precipitates fine mullite crystals around the mullite, forming a mullite whisker structure. This facilitates the effective fusion of mullite and the glass phase. The resulting glass coating provides excellent oxidation protection for the substrate material at 1200℃, significantly improving the high-temperature resistance, thermal insulation, surface wear resistance, and acid and alkali resistance of the ceramic coating material. This further broadens the high-temperature application environment for transparent oxynitride ceramics and makes it suitable for widespread application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-temperature anti-oxidation glass coating for transparent oxynitride ceramics is first prepared by using mullite powder and glass powder as the main raw materials to form a slurry, which is then coated on the surface of a transparent oxynitride ceramic substrate, followed by pre-curing and sintering. The glass powder contains 69-72 wt.% SiO2, 5-8 wt.% Al2O3, 9-10 wt.% CaO, and 8-9 wt.% ZnO.

[0008] In the above scheme, the mullite powder passes through a 200-mesh sieve.

[0009] In the above scheme, the mullite powder is obtained by dry grinding, calcination and pulverization of alumina and silica powder as raw materials.

[0010] Furthermore, the silica powder is dry-ground using alumina balls before use.

[0011] Furthermore, the molar ratio of the alumina and silica powder is 61-63:39-37.

[0012] In the above scheme, the mullite powder is calcined at a temperature of 1600-1700℃ for 2-3 hours.

[0013] In the above scheme, the particle size of the glass powder is 1 to 2 μm.

[0014] In the above scheme, the main chemical components and their mass percentages in the raw material used for the glass powder include: SiO2 69-72 wt.%; Al2O3 5-8 wt.%; ZnO 8-9 wt.%; K2O 3-5 wt.%; CaO 9-10 wt.%; MgO 0.8-1 wt.%; TiO2 0.2-0.4 wt.%; BaO 0.5-0.7 wt.%; ZrO2 0.2-0.4 wt.%; B2O3 0.4-0.6 wt.%.

[0015] In the above scheme, the high-temperature anti-oxidation glass coating is disposed on a transparent oxynitride ceramic substrate, specifically transparent ceramics such as MgAlON, AlON or LiAlON can be selected.

[0016] The preparation method of the above-mentioned transparent ceramic high-temperature anti-oxidation glass coating of oxynitride includes the following steps:

[0017] (1) Mix alumina powder and silica powder, dry grind, dry, crush and sieve to obtain mixed powder, then calcine, grind, dry, crush and sieve to obtain mullite powder;

[0018] (2) Weigh and mix the raw materials for glass in proportion, heat and melt them, then pour them into water to quench and agglomerate them, then crush and sieve them to obtain glass powder;

[0019] (3) Add mullite powder to glass powder, mix evenly, dry grind, wet grind, dry, and sieve to obtain mixed powder; use it to prepare slurry and coat it on a transparent oxynitride ceramic substrate;

[0020] (4) The ceramic-glass coating material obtained in step (3) is naturally dried and pre-cured at room temperature; then it is sintered at high temperature, rapidly cooled to the annealing temperature of 600-750℃, held for annealing for 2-3 hours, and then cooled by programmed cooling or furnace cooling to obtain the nitrogen oxide transparent ceramic high-temperature anti-oxidation glass coating.

[0021] In the above scheme, the ball-to-material ratio used in the dry grinding step (1) is (4-6):1, the rotation speed is (120-200r) / min, and the dry grinding time is 8-12h.

[0022] In the above scheme, the grinding step in step (1) adopts dry grinding and wet grinding processes, wherein the ball-to-material ratio is (4-6):1, the rotation speed is (120-200r) / min, the dry grinding time is 8-12h, and the wet grinding time is 18-24h.

[0023] In the above scheme, the sieving step before calcination in step (1) is to pass through a 100-mesh sieve, and the sieving step after calcination is to pass through a 200-mesh sieve.

[0024] In the above scheme, the heating and melting step in step (2) uses a temperature of 1500-1600℃ and a time of 5-10min.

[0025] In the above scheme, the mass ratio of glass powder to mullite powder in step (3) is 100:(5~10).

[0026] In the above scheme, the ball-to-material ratio used in the dry grinding and wet grinding steps in step (3) is (4-6):1, the rotation speed is (120-200r) / min, the dry grinding time is 8-12h, and the wet grinding time is 18-24h.

[0027] In the above scheme, the sieving in step (3) is to pass through a 200-mesh sieve (all powders pass through a 200-mesh sieve to eliminate powder agglomeration).

[0028] In the above scheme, the mass ratio of the mixed powder to the water-based printing ink is 1:(0.4~0.6).

[0029] In the above scheme, the printing step adopts screen printing process, wherein the mesh count of the screen is 160 to 200.

[0030] Furthermore, in the printing step, after each printing, drying is performed for 10 to 25 minutes at a temperature of 120 to 140°C until the target thickness is achieved.

[0031] In the above scheme, the target thickness of the printing step is 0.2 to 0.25 mm.

[0032] In the above scheme, in step (4), the pre-curing time is 12-36 hours; the high-temperature sintering temperature is 900-1300℃, the holding time is 15-20 minutes, and the atmosphere used is air (partial coating at 1000℃), nitrogen, or argon, etc., with a heating rate of 8-10℃ / min.

[0033] In the above scheme, the rapid cooling step in step (4) takes less than 30 minutes.

[0034] The nitrogen oxide transparent ceramic high-temperature anti-oxidation glass coating prepared according to the above scheme contains a mullite crystalline phase with a plate-like structure, wherein mullite whiskers are formed at the interface between the plate-like structure and the glass system.

[0035] The principle of this invention is as follows:

[0036] This invention uses oxynitride transparent ceramics as a matrix and introduces mullite powder into a molten high-silicon-aluminum-calcium-zinc-based glass system. During the high-temperature sintering process, the Al and Si-rich glass phase precipitates fine mullite crystals around the mullite, forming a mullite whisker structure. This can effectively improve the high-temperature resistance, thermal insulation, surface wear resistance, and acid and alkali resistance of the ceramic glass coating material. It also helps to fill defects such as pores and cracks generated by oxynitride transparent ceramics, effectively expanding the high-temperature application environment of oxynitride transparent ceramics.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1) In this invention, glass powder and mullite powder are mixed and then sintered at high temperature. The Al and Si-rich glass phase precipitates fine mullite crystals around the mullite and forms mullite whiskers, which facilitates the bonding between mullite and glass. This structure significantly improves the mechanical properties of the transparent glass coating. By adding an appropriate amount of mullite, the Vickers microhardness of the glass coating is significantly improved, while reducing wear loss.

[0039] 2) In the preparation process of the anti-oxidation glass coating described in this invention, raw materials such as alumina, silicon dioxide, calcium oxide, and zinc oxide are introduced to simultaneously optimize the expansion coefficient, firing temperature, and fluidity of the glass coating. In addition, the high content of calcium oxide and zinc oxide introduced into the glass powder increases the refractive index and approaches the mullite crystal, effectively reducing the scattering loss between the glass phase and mullite (which can be ignored), and effectively ensuring the high transparency of the obtained glass coating.

[0040] 3) By adjusting the ratio of glass raw material to mullite powder, this invention achieves high bonding strength and durability between the transparent ceramic matrix and the glass coating, good high-temperature chemical stability, and good high-temperature mechanical properties. Furthermore, the glass coating has a wide softening temperature range of 900–1300℃, which can effectively broaden the application environment of nitride transparent ceramics. Moreover, the preparation process involved is simple and the preparation cost is low, making it suitable for widespread application. Attached Figure Description

[0041] Figure 1 The images show the surface changes of MgAlON transparent ceramics with and without glass coatings in Example 1 at temperatures ranging from 600 to 1200°C.

[0042] Figure 2 The cross-sectional microstructures of the MgAlON-glass coating materials obtained in (a) Comparative Example 1 and (b) Comparative Example 2 are shown.

[0043] Figure 3 This is a scanning electron microscope image of the mullite crystals obtained in the glass coating of Example 1;

[0044] Figure 4The transmittance diagrams are for MgAlON / AlON transparent ceramic and MgAlON transparent ceramic-glass coating materials oxidized at 1200℃, respectively, within the range of 0.2 to 2.5 μm obtained from Examples 1 and 7.

[0045] Figure 5 Transmittance diagrams of MgAlON transparent ceramic and MgAlON / transparent ceramic-glass coating materials oxidized at 1200℃ within the range of 0.2–2.5 μm for the glass coating obtained in Comparative Example 2. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] In the following embodiments, the preparation method of the mullite powder includes the following steps: mixing silica powder (100 mesh) and alumina powder at a molar ratio of 61:39, ball milling to mix evenly with a ball-to-material ratio of 4:1 at a speed of 120 r / min, dry milling for 12 h, drying in a drying oven at 75°C for 24 h, crushing, and sieving through a 100 mesh to obtain a mixed powder; placing it in a high-temperature muffle furnace and calcining it at 1600°C for 2 h to obtain single-phase mullite powder, then dry milling for 12 h, wet milling for 24 h, drying in a drying oven at 75°C for 24 h, crushing, and sieving through a 200 mesh to obtain mullite powder.

[0048] The water-based ink used is a high-temperature glass ink provided by Foshan Taoyiseyou Co., Ltd., which is suitable for glass and ceramics and has the serial number 8010.

[0049] Example 1

[0050] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0051] 1) Using MgAlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix glass raw materials with mass fractions of 69.7% SiO2, 5.5% Al2O3, 8.8% ZnO, 3.7% K2O, 9.7% CaO, 1% MgO, 0.3% TiO2, 0.6% BaO, 0.3% ZrO2, and 0.4% B2O3 according to the proportions, melt them at 1500℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 5g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-material ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0052] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.5, and apply it to the MgAlON transparent ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120℃ for 10 minutes. Repeat the above operation 8 to 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0053] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1200℃ and held for 20 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours. After that, it is naturally cooled with the furnace to obtain the antioxidant glass coating (ceramic-glass coating).

[0054] Example 2

[0055] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0056] 1) Using MgAlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix glass raw materials with mass fractions of 69.7% SiO2, 5.5% Al2O3, 8.8% ZnO, 3.7% K2O, 9.7% CaO, 1% MgO, 0.3% TiO2, 0.6% BaO, 0.3% ZrO2, and 0.4% B2O3 according to the proportions, melt them at 1550℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 5g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-material ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0057] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.55, and apply it to the MgAlON transparent ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120℃ for 10 minutes. Repeat the above operation 8 to 10 times, and measure the layer thickness as 0.2 to 0.25 mm.

[0058] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1250℃ and held for 20 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours. After that, it is naturally cooled with the furnace to obtain the antioxidant glass coating.

[0059] Example 3

[0060] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0061] 1) Using MgAlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use. Weigh and mix glass raw materials with the following mass fractions: 71.2% SiO2, 6% Al2O3, 8% ZnO, 3.3% K2O, 9.1% CaO, 0.9% MgO, 0.4% TiO2, 0.5% BaO, 0.2% ZrO2, and 0.4% B2O3. Melt the mixture at 1500℃ and pour it into water to form a floc. Crush the floc and sieve it to obtain glass powder. Add 8g of mullite powder to 100g of glass powder, ball mill to mix, with a ball-to-powder ratio of 4:1, at a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use.

[0062] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.55, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each layer is printed, dry it in a drying oven at 120°C for 10 minutes. Repeat the above operation 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0063] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1250℃ and held for 20 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours to obtain the antioxidant glass coating.

[0064] Example 4

[0065] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0066] 1) Using MgAlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix the glass raw materials with a mass fraction of 71.2% SiO2, 6% Al2O3, 8% ZnO, 3.3% K2O, 9.1% CaO, 0.9% MgO, 0.4% TiO2, 0.5% BaO, 0.2% ZrO2, and 0.4% B2O3 according to the proportion, melt them at 1550℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 8g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-powder ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0067] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.5, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120°C for 10 minutes. Repeat the above operation 8 to 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0068] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1300℃ and held for 15 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours. After that, it is naturally cooled with the furnace to obtain the antioxidant glass coating.

[0069] Example 5

[0070] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0071] 1) Using MgAlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix the glass raw materials with a mass fraction of 72% SiO2, 5.1% Al2O3, 8.2% ZnO, 3.6% K2O, 9% CaO, 0.8% MgO, 0.2% TiO2, 0.5% BaO, 0.2% ZrO2, and 0.4% B2O3 according to the proportion, melt them at 1500℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 10g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-material ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0072] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.55, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120℃ for 10 minutes. Repeat the above operation 8 to 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0073] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1250℃ and held for 20 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours. After that, it is naturally cooled with the furnace to obtain the antioxidant glass coating.

[0074] Example 6

[0075] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0076] 1) Using MgAlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix the glass raw materials with a mass fraction of 72% SiO2, 5.1% Al2O3, 8.2% ZnO, 3.6% K2O, 9% CaO, 0.8% MgO, 0.2% TiO2, 0.5% BaO, 0.2% ZrO2, and 0.4% B2O3 according to the proportion, melt them at 1550℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 10g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-material ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0077] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.55, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a 120℃ drying oven for 10 minutes. Repeat the above operation 8 to 10 times, and measure the layer thickness as 0.2 to 0.25 mm.

[0078] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1300℃ and held for 15 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours. After that, it is naturally cooled with the furnace to obtain the antioxidant glass coating.

[0079] Example 7

[0080] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0081] 1) Using AlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix the glass raw materials with a mass fraction of 69.7% SiO2, 5.5% Al2O3, 8.8% ZnO, 3.7% K2O, 9.7% CaO, 1% MgO, 0.3% TiO2, 0.6% BaO, 0.3% ZrO2, and 0.4% B2O3 according to the proportion, melt them at 1500℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 5g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-material ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0082] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.5, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120°C for 10 minutes. Repeat the above operation 8 to 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0083] 3) The obtained ceramic-glass coating material is naturally dried at room temperature and then left to stand for 36 hours for pre-curing. The pre-cured coating is placed in a nitrogen atmosphere heat treatment furnace, and the heating rate is maintained at 10℃ / min. The temperature is raised to 1200℃ and held for 20 minutes. Then, it is rapidly cooled to 750℃ within 30 minutes and held for 2 hours. After that, it is naturally cooled with the furnace to obtain the antioxidant glass coating.

[0084] Example 8

[0085] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0086] 1) Using AlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix the glass raw materials with a mass fraction of 71.2% SiO2, 6% Al2O3, 8% ZnO, 3.3% K2O, 9.1% CaO, 0.9% MgO, 0.4% TiO2, 0.5% BaO, 0.2% ZrO2, and 0.4% B2O according to the proportion, melt it at 1500℃ and pour it into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 8g of mullite powder to 100g of glass powder, ball mill and mix it evenly with a ball-to-powder ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass it through a 200-mesh sieve for later use;

[0087] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.55, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120℃ for 10 minutes. Repeat the above operation 8 to 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0088] 3) Allow the obtained ceramic-glass coating material to air dry naturally at room temperature, and then let it stand for 36 hours for pre-curing. Place the pre-cured coating in a nitrogen atmosphere heat treatment furnace, maintain a heating rate of 10℃ / min, heat to 1250℃, hold for 20 minutes, then rapidly cool to 750℃ within 30 minutes, hold for 2 hours, and then allow it to cool naturally with the furnace to obtain the antioxidant glass coating.

[0089] Example 9

[0090] A transparent oxynitride ceramic high-temperature anti-oxidation glass coating, the preparation method of which includes the following steps:

[0091] 1) Using AlON transparent ceramic as a substrate, ultrasonically clean it with anhydrous ethanol for 15 min, then rinse it repeatedly with distilled water, and dry it for later use; weigh and mix the glass raw materials with a mass fraction of 71.2% SiO2, 6% Al2O3, 8% ZnO, 3.3% K2O, 9.1% CaO, 0.9% MgO, 0.4% TiO2, 0.5% BaO, 0.2% ZrO2, and 0.4% B2O3 according to the proportion, melt them at 1500℃ and pour them into water to form a floc. After crushing the floc, sieve it to obtain glass powder. Add 8g of mullite powder to 100g of glass powder, ball mill and mix them evenly at a ball-to-powder ratio of 4:1 and a speed of 120r / min. Dry mill for 12h, wet mill for 24h, dry in a drying oven at 75℃ for 24h, and pass through a 200-mesh sieve for later use;

[0092] 2) Mix the obtained powder with water-based printing ink at a mass ratio of 1:0.5, and apply it to the ceramic substrate by screen printing using a 160-mesh screen. After each printing, dry it in a drying oven at 120°C for 10 minutes. Repeat the above operation 8 to 10 times and measure the layer thickness as 0.2 to 0.25 mm.

[0093] 3) Allow the obtained ceramic-glass coating material to air dry naturally at room temperature, and then let it stand for 36 hours for pre-curing. Place the pre-cured coating in a nitrogen atmosphere heat treatment furnace, maintain a heating rate of 10℃ / min, heat to 1250℃, hold for 20 minutes, then rapidly cool to 750℃ within 30 minutes, hold for 2 hours, and then allow it to cool naturally with the furnace to obtain the antioxidant glass coating.

[0094] Comparative Example 1

[0095] The difference between this example and Example 1 is that the powder used to prepare the coating slurry does not contain mullite powder, while the chemical composition and weight percentage of other glass powders remain unchanged.

[0096] Comparative Example 2

[0097] The difference between this example and Example 1 is that in step 1), the glass raw materials are mixed in the following proportions: 52% SiO2, 0.8% Al2O3, 0.8% ZnO, 8% K2O, 2% CaO, 15% MgO, 4% TiO2, 5% BaO, 6.2% ZrO2, and 6.2% B2O3.

[0098] It is further emphasized that the present invention uses a nitrogen atmosphere, and the effect obtained is the same as that obtained in actual air (partial coating at 1000°C) and argon atmosphere.

[0099] The relevant mechanical property data of the ceramic-glass coatings obtained in Examples 1-9 and Comparative Examples 1-2 of this invention are shown in Table 1.

[0100] Table 1. Mechanical property test results of ceramic-glass coatings obtained in Examples 1-9 and Comparative Examples 1-2

[0101] serial number Vickers hardness (GPa) Mass loss (mg) Example 1 7.12 139 Example 2 7.11 138 Example 3 7.15 135 Example 4 7.16 134 Example 5 7.18 132 Example 6 7.18 131 Example 7 7.12 138 Example 8 7.15 134 Example 9 7.14 133 Comparative Example 1 6.76 185 Comparative Example 2 6.95 165

[0102] Among them, the mass loss is determined according to ISO 10545-7:1996, by measuring the weight loss after 6000 revolutions using an abrasion tester to determine the wear resistance.

[0103] Table 1 shows that in Examples 1-9, the Vickers hardness of the glass coating increases and the mass loss decreases with increasing mullite powder content, exhibiting better mechanical properties. The glass coatings obtained in Comparative Examples 1-2 show poorer hardness and wear resistance.

[0104] like Figure 1 As shown, at temperatures ranging from 600 to 1200°C, the ceramic glass coating prepared in Example 1 provides good protection at 1200°C. However, for transparent ceramics without a glass coating, a hazy appearance forms on the surface at 1000°C, affecting the transparency of the transparent ceramics.

[0105] The cross-sectional microstructure of the products obtained in Comparative Examples 1 and 2 is shown in Figure (2). Figure 2 (a) is the glass coating obtained in Comparative Example 1, which is smooth and glossy, but has poor wear resistance; (b) is the glass coating obtained in Comparative Example 2, where cracks and bubbles can be found, affecting the performance of the glass coating.

[0106] Figure 3 The image shows the morphology of localized mullite blocky crystals in the glass coating obtained in Example 1. It can be observed that the mullite crystals within the coating are plate-like with irregular planar shapes. Small mullite crystals precipitated in the Al and Si-rich glass phase connect with mullite crystals produced during the sintering of mullite powder, forming a whisker structure. The mullite phase can further react and fuse with the glass phase in later stages, thereby improving the glass's wear resistance and effectively reducing the impact of mullite crystals on the transparency of the glass coating.

[0107] Depend on Figure 4 It can be seen that the transmittance of the MgAlON-glass coatings prepared in Examples 1 and 7, and the sample AlON-glass coatings, in the range of 0.2–2.5 μm is not significantly different from that of the original transparent ceramic, indicating that the glass coatings have good optical properties. Figure 5 It can be seen that the optical properties of the glass coating on the MgAlON transparent ceramic in Comparative Example 2 are poor.

[0108] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A nitric oxide transparent ceramic high temperature oxidation resistant glass coating, characterized in that, Its preparation method includes the following steps: (1) Mix alumina powder and silica powder, dry grind, dry, crush and sieve to obtain mixed powder, then calcine, grind, dry, crush and sieve to obtain mullite powder; (2) Weigh and mix the raw materials for glass according to the proportion, heat and melt them, then pour them into water for quenching and agglomeration, then crush and sieve them to obtain glass powder; the glass powder contains 69~72 wt.% SiO2, 5~8 wt.% Al2O3, 9~10 wt.% CaO, and 8~9 wt.% ZnO; the main chemical components and their mass percentages in the raw materials used for glass powder include: SiO2 69~72 wt.%; Al2O3 5~8 wt.%; ZnO 8~9 wt.%; K2O 3~5 wt.%; CaO 9~10 wt.%; MgO 0.8~1 wt.%; TiO2 0.2~0.4 wt.%; BaO 0.5~0.7 wt.%; ZrO2 0.2~0.4 wt.%; B2O3 0.4~0.6 wt.% wt.%% (3) Add mullite powder to glass powder, mix evenly, dry grind, wet grind, dry, and sieve to obtain mixed powder; use it to prepare slurry and coat it on oxynitride transparent ceramic substrate; the mass ratio of glass powder to mullite powder is 100: (5~10). (4) The ceramic-glass coating material obtained in step (3) is naturally dried and pre-cured at room temperature; then it is sintered at high temperature, rapidly cooled to the annealing temperature of 600~750℃, held for annealing for 2~3 hours, and then cooled by program or furnace cooling to obtain the nitrogen oxide transparent ceramic high temperature anti-oxidation glass coating. The prepared nitrogen oxide transparent ceramic high-temperature anti-oxidation glass coating contains a mullite crystalline phase with a plate-like structure, wherein mullite whiskers are formed at the interface between the plate-like structure and the glass system.

2. The nitroxide transparent ceramic high-temperature oxidation resistant glass coating according to claim 1, characterized in that, The mullite powder is calcined at a temperature of 1600~1700℃ for 2~3 hours.

3. The nitrogen oxide transparent ceramic high-temperature anti-oxidation glass coating according to claim 1, characterized in that, The slurry coating method is printing, spraying, or dipping.

4. The nitrogen oxide transparent ceramic high-temperature anti-oxidation glass coating according to claim 1, characterized in that, The nitrogen oxide transparent ceramic matrix is ​​MgAlON, AlON or LiAlON transparent ceramic.

5. The method for preparing the nitrogen oxide transparent ceramic high-temperature antioxidant glass coating according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Mix alumina powder and silica powder, dry grind, dry, crush and sieve to obtain mixed powder, then calcine, grind, dry, crush and sieve to obtain mullite powder; (2) Weigh and mix the raw materials for glass according to the proportion, heat and melt them, then pour them into water for quenching and agglomeration, then crush and sieve them to obtain glass powder; the glass powder contains 69~72 wt.% SiO2, 5~8 wt.% Al2O3, 9~10 wt.% CaO, and 8~9 wt.% ZnO; the main chemical components and their mass percentages in the raw materials used for glass powder include: SiO2 69~72 wt.%; Al2O3 5~8 wt.%; ZnO 8~9 wt.%; K2O 3~5 wt.%; CaO 9~10 wt.%; MgO 0.8~1 wt.%; TiO2 0.2~0.4 wt.%; BaO 0.5~0.7 wt.%; ZrO2 0.2~0.4 wt.%; B2O3 0.4~0.6 wt.% wt.%% (3) Add mullite powder to glass powder, mix evenly, dry grind, wet grind, dry, and sieve to obtain mixed powder; use it to prepare slurry and coat it on oxynitride transparent ceramic substrate; the mass ratio of glass powder to mullite powder is 100: (5~10). (4) The ceramic-glass coating material obtained in step (3) is naturally dried and pre-cured at room temperature; then it is sintered at high temperature, rapidly cooled to the annealing temperature of 600~750℃, held for annealing for 2~3 hours, and then cooled by program or furnace cooling to obtain the nitrogen oxide transparent ceramic high temperature anti-oxidation glass coating. The prepared nitrogen oxide transparent ceramic high-temperature anti-oxidation glass coating contains a mullite crystalline phase with a plate-like structure, wherein mullite whiskers are formed at the interface between the plate-like structure and the glass system.

6. The preparation method according to claim 5, characterized in that, The heating and melting step is performed at a temperature of 1500~1600℃ for 5~10 minutes.

7. The preparation method according to claim 5, characterized in that, In step (4), the pre-curing time is 12~36h; the high-temperature sintering temperature is 900~1300℃, the holding time is 15~20min, and the atmosphere used is air, nitrogen or argon.

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